Valsartan, N-(1-oxopentyl)-N-[[2′-(1H-tetrazol-5-yl)[1,1′-biphenyl]-4yl]methyl]-L-valine, is a known anti-hypertensive agent having the following formula (I):

Valsartan is a non-peptide, orally active, specific angiotensin II antagonist, useful in the treatment of hypertension and is commercially available in the market under the brand name DIOVAN™ as 40, 80, 160 and 320 mg tablets.
Valsartan, its pharmaceutically acceptable salts, pharmaceutical compositions comprising valsartan and their use in treating high blood pressure and cardiac insufficiency are disclosed in U.S. Pat. No. 5,399,578 along with its preparation as depicted in scheme 1.

Briefly, the process for the preparation of Valsartan comprises the condensation of compound of formula IV with Valeryl chloride of formula III in the presence of triethylamine and dichloromethane followed by flash chromatography, to give the compound of formula II. The compound of formula II during tetrazole formation is undergo reaction with tributyltin azide and then subsequently hydrolysis using base like sodium hydroxide followed by flash chromatography gives Valsartan of formula I.
The preparation of Valsartan according to the scheme reported above is very complicated and not commercially viable. The synthetic process which involves, inter-alia the use of tributyltin azide leads to increase the tin content in final product as an impurity approx. 20 ppm. It would therefore be highly desirable to provide a process the preparation of substantially pure valsartan, which is commercially viable as well as reduces/removes the contamination of tin content in the final product i.e., Valsartan.
It has now been found an alternative process for the preparation of substantially pure Valsartan which fulfills the above mentioned requirements.